1. Field of the Invention
The present invention relates to a light emitting diode (LED) array employable in an electronic printer for photolithography, and particularly to the structure of a plurality of interconnection conductors in the LED array.
2. Description of the Related Art
FIG. 8 is a schematic top plan view showing light emitting diodes (LEDs) 10 in a portion of a prior art LED array 12. FIG. 9 is a cross-sectional view taken along line 9--9 of Fig 8.
The process of fabricating the prior art light emitting diode array 12 to as follows:
First, an Al.sub.2 O.sub.3 layer 14 acting as a diffusion prevention layer is formed in a N-GaAs substrate 16. Then, an insulating layer 18 such as S.sub.3 N.sub.4 is formed on the Al.sub.2 O.sub.3 layer 14. Then, a P-type impurity such as Zn is diffused Into portions of the surface of the N-GaAs substrate 16 that are not covered by the Al.sub.2 O.sub.3 layer 14 and the insulating layer 18 by the vapor diffusion method. As a result, p-GaAsP regions 20 are formed in the N-GaAs substrate 16. The regions 20 act as light emitting areas.
Then, interconnection conductors 22 are formed. The interconnection conductors 22 are in ohmic contact with the p-GaAsP regions 20, and extend from the regions 20 over stepped portions 24 to the top surface of the insulating layer 14. In this application, a "stepped portion" of a conductor refers to a portion of the conductor where its height or level changes abruptly in one or more steps.